1. Field of the Invention
The present invention generally relates to a platinum complex and an organic light-emitting element using the same.
2. Description of the Related Art
Light-emitting elements have been actively developed with the object of providing organic LED elements having stable, highly efficient emission. In particular, phosphorescent light-emitting elements using phosphorescence typically have good emission efficiency of the elements themselves. Accordingly, phosphorescent light-emitting materials that are components of phosphorescent light-emitting elements have been intensively developed. A cyclometalated iridium complex of an Ir(C—N)3 type or (C—N)2Iracac type in which a cyclometalated bidentate ligand (C—N ligand, referred to hereinbelow simply as C—N) is coordinated to a metal atom has been disclosed in “Highly Phosphorescent Bis-Cyclometalated Iridium Complexes: Synthesis, Photophysical Characterization, and Use in Organic Light Emitting Diodes”, Lamansky, S.; Djurovich, P.; Murphy, D.; Abdel-Razzaq, F.; Lee, H.-E.; Adachi, C.: Burrows, P. E.: Forrest, S. R.; Thompson, M. E. J. Am. Chem. Soc.; 2001; 123 (18); 4304-4312. Also developed have been cyclometalated platinum complexes as disclosed in “Synthesis and Characterization of Phosphorescent Cyclometalated Platinum Complexes” Brooks, J.; Babayan, Y.; Lamansky, S.; Djurovich, P. I.; Tsyba, I.; Bau, R.; Thompson, M. E. Inorg. Chem; 2002; 41 (12); 3055-3066.
However, there remains a need for elements with a light output of even higher luminance and a higher conversion efficiency. Furthermore, in certain instances, the durability of the elements may not be sufficient, with insufficient durability often being associated with degradation in long-term use and resistance to oxygen-containing atmosphere and moisture. In addition, blue, green, and red light emission with good color purity may be necessary when applications to full-color displays and the like are considered. Thus, there remains a need for improved durability and color purity.
Tetravalent platinum complex compounds composed of three bidentates having bipyridine or phenanthroline as a ligand have been disclosed in “Organoplatinum (IV) tris-chelate complexes, each having a cyclic metallacarbonate ring: synthesis, characterization and kinetics studies of the formation” Rashidi, M.; Shahabadi, N.; Nabavizadeh, M. S. Dalton Trans.; 204; 619-622.
Japanese Patent Laid-Open No. 2001-181617 and International Publication No. WO 2006/067074 disclose the application of particular platinum complexes to organic light-emitting elements. More specifically, Japanese Patent Laid-Open No. 2001-181617 discloses the application of a divalent platinum complex material to an organic light-emitting element. International Publication No. WO 2006/067074 discloses the application of a divalent platinum complex material having a carbene ligand to an organic light-emitting element.